1. Field of the Invention
The present invention relates to a portable apparatus used for electric field communication in which information signals are transmitted and/or received via a transmission medium such as a human body or space.
2. Description of the Related Art
Regarding a communication system in which transmission/reception is performed via a transmission medium (mainly a human body), a method of communication using an electric field is disclosed in, for example, PCT Japanese Translation Patent Publication No. 11-509380. Referring to FIG. 11, a transmitter and a receiver disclosed in PCT Japanese Translation Patent Publication No. 11-509380 each include an electrode pair, i.e., a pair of a human body side (inner) electrode 111 having close capacitive coupling with a human body 112 and an outer electrode 113 that is arranged in such a manner as to have stronger coupling with the room ground than the human body side (inner) electrode 111. The pair of electrodes are plate-shaped and arranged to be parallel to each other, as illustrated in FIG. 11.
When the above technology is applied to portable apparatuses, it is important to design the electrodes appropriately, and it is necessary to devise transmission/reception electrodes, i.e., transmission-medium-side electrodes. In view of deterioration in communication quality caused when unnecessary electromagnetic waves, generated from electronic circuits or a display of a portable terminal for electric field communication, penetrate into a transmission medium such as a human body, Japanese Unexamined Patent Application Publication No. 2005-303922 discloses that transmission/reception electrodes for electric field communication are newly provided at positions away from the circuit components (such as a display, operation keys, an electric field communication transceiver, and a computer) of a portable terminal for electric field communication, thereby suppressing penetration of unnecessary electromagnetic waves generated from the circuit components into a transmission medium, and improving communication quality.